JP2002071431A - Liquid level sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact type liquid level sensor having adequate durability. SOLUTION: This sensor is provided with a plurality of sensing elements for detection 1a-1h located in line along the liquid depth direction, a sensing element for reference 1x located adjacent to these sensing elements 1a-1h, a float 4 vertically moving along the aligned direction of these sensing elements 1a-1h depending on the liquid level F position of the above liquid, a magnet 5 placed on this float 4 vertically moving near these sensing elements 1a-1h while facing them, and a processing means measuring mobility of the float 4 from the outputs of both the sensing elements 1a-1h and the sensing element 1x.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level sensor for detecting a liquid level with a float that moves up and down in response to a change in the liquid level of the liquid.

[0002]

2. Description of the Related Art As a liquid level sensor for detecting a liquid level by a float that moves up and down in response to a change in the liquid level, for example, a liquid level sensor 01 for detecting the remaining amount of fuel in a vehicle or the remaining amount of oil in a hydraulic system circuit. A virtual type as shown in FIG. 5 is known. In this configuration, a longitudinal variable resistor 04 is arranged in a vertical direction in a main body portion 03 into which a liquid 02 can flow, and the main body portion 03 moves up and down in accordance with the vertical movement of the liquid surface of the liquid 02. A float 05 is arranged, and the float 05 is integrally provided with a contact 07 slidably contacting the electrode 06 of the variable resistor 04, and the contact 07 moves up and down in accordance with the up and down movement of the float 05. Thus, the resistance value of the variable resistor 04 changes according to the liquid level of the liquid 02.

[0003]

The liquid level sensor 01 having such a configuration has a problem that durability is deteriorated due to sliding friction between the electrode 06 and the contact 07.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a durable liquid level sensor having a non-contact structure.

[0005]

According to a first aspect of the present invention, there is provided a liquid level sensor according to the present invention.
A plurality of sensing elements for detection located in a line along the depth direction of the liquid, one reference sensing element located in the vicinity of the sensing element, and A float that moves up and down according to the arrangement direction of the sensing elements for detection, and a magnet that is arranged on the float and moves up and down while facing the sensing element in the vicinity of the sensing element for detection,
Processing means for measuring the amount of movement of the float from outputs of the sensing element for detection and the sensing element for reference.

Thus, a non-contact type durable liquid level sensor can be realized.

According to another aspect of the present invention, a plurality of sensing elements for detection are arranged in a line in the depth direction of the liquid, and one reference element located near the sensing element. A sensing element, a float that moves up and down in accordance with the arrangement direction of the sensing element for detection according to the liquid surface position of the liquid, and the vicinity of the sensing element for detection arranged on the float and facing the sensing element. A magnetic body moving up and down, and a magnet facing the magnetic body with the sensing element for detection interposed therebetween,
Processing means for measuring the amount of movement of the float from outputs of the sensing element for detection and the sensing element for reference.

As a result, a non-contact type durable liquid level sensor can be realized.

According to a third aspect of the present invention, there is provided a rotary plate for performing a rotary motion in accordance with a vertical movement of a float in accordance with a liquid surface position, and a plurality of rotary plates positioned along a peripheral edge of an upper surface of the rotary plate. A magnetic element, and a sensing element which is located above the rotation range of the magnetic element and whose output changes every time the magnetic element passes,
Processing means for measuring the amount of movement of the float by measuring the amount of movement of the rotary plate from the output of the sensing element.

As a result, it is possible to realize a non-contact type highly durable liquid level sensor.

[0011] In particular, in the first to third aspects, as described in the fourth aspect, the sensing element is a magnetoresistive element or a Hall element.

[0012] This makes it possible to realize a non-contact type durable liquid level sensor, and in particular, to use a liquid crystal element or a Hall element, which is relatively easy to handle and inexpensive, and is easy to manufacture. A surface sensor can be realized.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described based on embodiments shown in the accompanying drawings.

In FIGS. 1 and 2 showing the first embodiment,
A plurality of sensing elements, for example, eight magnetoresistive elements for detection 1a to 1h having the same characteristics and one magnetoresistive element for reference 1x are arranged in a line along the depth direction of the liquid. A donut-shaped float 4 that is vertically arranged along the height direction of the cylinder 2 of the substrate 3 disposed vertically in the cylinder 2 and that moves up and down according to the liquid level F of the liquid is provided around the cylinder 2.
The float 4 has the magnetoresistive elements 1a to 1a.
The magnet 5 is arranged so as to face 1h.

Although the magnetoresistive elements 1a to 1h have the same characteristics, they can be used in combination with different characteristics, and are arranged at equal intervals.
It is also possible to make the intervals different in order to obtain predetermined characteristics.

Reference numeral 6 denotes an outer cylinder, which constitutes a housing together with the inner cylinder 2, and an opening located at the upper end of the housing has:
The lid 7 is sealed in a watertight manner.

The wires of the magnetoresistive elements 1a to 1h and 1x are drawn out from the lid 7, and the magnetoresistive elements 1a to 1h are electrically connected in parallel.
The liquid surface F is detected by sequentially connecting the pieces and the magnetoresistive element 1x in series and measuring the midpoint potential (voltage) at the connection point.

That is, as shown in FIG. 2, a power supply V is connected to a series circuit of the magnetoresistive elements 1a to 1h and the magnetoresistive element 1x.
cc is connected, and the midpoint voltage Vc is input to the measurement terminal IN1 of the comparator C. On the other hand, the power supply Vc is connected to the resistors R1 and R2.
Of the comparator C as a predetermined reference voltage Vs
To the reference terminal IN2. Magnetic resistance elements 1a to 1h
Since the resistance value of the magnet 5 close to the former (the former) and the resistance of the magnet 5 not close to the latter (the latter) are different, by serially connecting one of them and the magnetoresistive element 1x in series, The midpoint voltage Vc in the former case is approximately Vcc / 2, but the midpoint voltage Vcc in the latter case is any other value.

Therefore, the reference terminal IN2 of the comparator C
By setting the reference voltage Vs input to the comparator C,
In the former case, the level of the output terminal OUT is set to low (off), and in the latter case, the level of the output terminal OUT is set to high (on).
Is monitored by a processing means such as a microcomputer (microcomputer), the position of the magnet 5, that is, the liquid level F, which is the position of the float 4, can be detected. The liquid level can be displayed on a display unit (not shown) such as a digital display element or the like by a predetermined display design.

The serial connection of one of the magneto-resistive elements 1a to 1h and the magneto-resistive element 1x in series can be realized by, for example, switching by repetition at a constant period by the microcomputer.

In place of the magnet 5 provided on the float 4, a magnetic material such as an iron piece can be used. In this case, a magnetic material is emitted between the magnet that emits magnetism to the magnetic material and the magnetic material. The configuration is such that the resistance elements 1 a to 1 h are arranged, and the magnet is arranged on the substrate 3.

In FIGS. 3 and 4 showing the second embodiment,
A float 12 is attached to one end of the lever 11, and a semicircular gear 13 is attached to the other end of the lever 11, and a gear 15 fixed to one end of a center shaft 14 meshes with the gear 13. The center shaft 14 is housed in a cylindrical body 16, a housing 17 is provided at an upper end of the body 16, and a magnet 18 is fixed to the other end of the center shaft 14. Therefore, the vertical movement of the float 12 causes the center shaft 14
Perform a rotational motion, and the magnet 18 rotates accordingly.

A magnet 19 facing the magnet 18 is rotatably provided inside the housing 17.
A circular rotating plate 20 interlocking with 8 is arranged on the upper surface of the magnet 19. A plurality of magnetic materials, for example, eight circular iron pieces 21a of the same shape, are formed on the upper surface of the rotating plate 20 along the periphery.
~ 21h are arranged at equal intervals, this iron piece 21a ~
A sensing element, for example, a magneto-resistive element 22 is disposed above the rotation range of 21 h. Above the magneto-resistive element 22, an iron piece 21 is sandwiched by the magneto-resistive element 22.
a to 21h are opposed to each other, and a magnet 23 is disposed between the magnet 23 and the housing 17.
It is fixed to.

Therefore, when the rotating plate 20 rotates, the iron pieces 21a to 21h located below the magnetoresistive element 22 change, and the magnetoresistive element 22 becomes opposed to the iron pieces 21a to 21h.
The output will change each time.

In such a configuration, for example, a change in the output of the magnetoresistive element 22 is counted by a processing means such as a microcomputer, so that the rotation distance of the rotating plate 20, ie, the rotation angle of the magnet 19 = the rotation angle of the magnet 18, ie, The amount of rotation of the center shaft 14, that is, the amount of vertical movement of the float 12 can be known, and the liquid level F of the liquid can be detected. No) and the liquid level can be displayed with a predetermined display design.

When the power is turned on again after the power is turned off, the current state of the magnetoresistive element 22 cannot be known. For example, when the liquid is full, the magnetoresistive element 22 is reset. A storage unit for storing (the number of changes), for example, a storage unit including a nonvolatile memory is prepared. Further, in order to detect a change in the output of the magnetoresistive element 22, the processing means performs a predetermined cycle (time)
To confirm the output of the magnetoresistive element 22.

As described above, such a liquid level sensor has a configuration in which the liquid level is detected by a non-contact type, so that the durability does not deteriorate due to sliding friction as in the related art.

The sensing element is not limited to the magneto-resistive element, but may be a so-called magneto-electric conversion element such as a Hall element. An effect can be obtained, and in particular, by using an inexpensive magnetoresistive element or a Hall element that is relatively easy to handle, a liquid level sensor that can be easily manufactured can be realized.

[0029]

According to the present invention, since it is a non-contact type, it is possible to realize a highly durable liquid level sensor.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a liquid level sensor according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of the same liquid level sensor.

FIG. 3 is an essential part cross-sectional view of a liquid level sensor according to a second embodiment of the present invention.

FIG. 4 is an explanatory view of a main part of the liquid level sensor.

FIG. 5 is a sectional view of a main part of a conventional technique.

[Explanation of symbols]

 1a-1h Magneto-resistive element for sensing (sensing element) 1x Magneto-resistive element for reference (sensing element) 3 Substrate 4 Float 5 Magnet 12 Float 18 Magnet 19 Magnet 20 Rotating plate 21a-21h Iron piece 22 Magnetoresistive element (Sensing element) ) 23 Magnet F Liquid level

Claims (4)

[Claims] 1. A plurality of sensing elements for detection positioned in a line in a depth direction of a liquid, one reference sensing element positioned near the sensing elements, and a liquid level of the liquid. A float that moves up and down in accordance with an arrangement direction of the sensing elements for detection according to a position, a magnet that is arranged on the float and moves up and down in the vicinity of the sensing element for detection while facing the sensing element; A sensor for measuring the amount of movement of the float from the outputs of the sensing element for reference and the sensing element for reference. 2. A plurality of sensing elements for detection arranged in a line in the depth direction of the liquid, one reference sensing element located near the sensing element, and a liquid level of the liquid. A float that moves up and down in accordance with the arrangement direction of the sensing elements for detection according to a position, a magnetic body that is arranged on the float and moves up and down while facing the sensing element in the vicinity of the sensing element for detection, A magnet opposing the magnetic body with a sensing element for detection interposed therebetween, and processing means for measuring a movement amount of the float from outputs of the sensing element for detection and the sensing element for reference. Characteristic liquid level sensor. 3. A rotary plate that performs a rotary motion in accordance with a vertical movement of a float in accordance with a liquid surface position, a plurality of magnetic bodies located along a peripheral edge of an upper surface of the rotary plate, and a rotation of the magnetic body. A sensing element which is located above the moving range and whose output changes each time the magnetic body passes therethrough, and a processing means for measuring the moving amount of the float by measuring the moving amount of the rotary plate from the output of the sensing element. , A liquid level sensor. 4. The liquid level sensor according to claim 1, wherein the sensing element is a magnetoresistive element or a Hall element.